Cracking process and catalyst for same containing indium to passivate contaminating metals

ABSTRACT

A novel cracking catalyst, a method of preparing same, and an improved hydrocarbon cracking process are provided wherein the adverse effects of metals such as nickel, vanadium, iron, copper, and cobalt on the cracking catalyst are reduced by contacting the cracking catalyst with a sufficient amount of at least one indium modifier selected from the group consisting of elemental indium and indium compounds free of the element antimony.

Hydrocarbon feedstock containing higher molecular weight hydrocarbons iscracked by contacting it at an elevated temperature with a crackingcatalyst whereby distillates such as gasoline and higher-boilinghydrocarbon fuels, e.g., kerosene, diesel fuel, burning oils and thelike, are produced. However, the cracking catalyst graduallydeteriorates during this process. One reason for this deterioration isthe deposition of contaminating metals such as nickel, vanadium, iron,copper and cobalt on the catalyst, resulting in increased production ofhydrogen and coke and decreased catalyst activity for cracking.Furthermore, the conversion of hydrocarbons into gasoline andhigher-boiling hydrocarbon fuels is reduced by these metals. Therefore,there is a need for a cracking process or a modified cracking catalystwhich will prevent or reduce the deleterious effects of these metalcontaminants.

It is thus an object of the present invention to provide an improvedcatalytic cracking process.

Another object of this invention is to provide a process for thepassivation of contaminating metals deposited on a cracking catalyst.

Another object of this invention is to provide a process for restorationof used cracking catalyst.

Another object of this invention is to provide a modified crackingcatalyst.

Another object of this invention is to provide a cracking catalyst whichprovides high yields and selectivity for gasoline or higher-boilinghydrocarbon fuel, e.g., kerosene, diesel fuel or burning oil.

Other aspects, objects and the several advantages of the invention willbe readily apparent to one skilled in the art from a reading of thefollowing disclosure and the appended claims.

In accordance with the present invention the adverse effects of nickel,vanadium, iron, copper, and/or cobalt or other similar contaminatingmetals can be reduced by contacting the cracking catalyst with asufficient amount of at least one modifier selected from the groupconsisting of elemental indium and indium compounds free of the elementantimony.

The indium modifier can be employed in any amount which is sufficient toreduce the deleterious effects that metals such as nickel, vanadium,iron, copper, and cobalt have on the activity of cracking catalysts.Generally, the modifier is used in such an amount as to provide about0.005 to about 8 weight percent, preferably about 0.01 to 2 weightpercent, of indium on the catalyst, this percentage being based on theweight of the catalyst prior to the addition of the indium modifier.

By the addition of the indium modifier to the cracking catalyst inaccordance with the present invention either prior to, during or afterits use in the cracking of feed containing catalyst contaminating metalsis achieved at least one of an increase in catalyst activity, anincrease in yield of gasoline or higher-boiling hydrocarbon fuels, e.g.,kerosene, diesel fuel, burning oils or the like, a decrease in theproduction of coke and a decrease in the production of hydrogen.

In accordance with one embodiment of this invention, a novel crackingcatalyst is provided that has been prepared by contacting a conventionalcracking catalyst with indium modifier in an amount and in a manner asherein described.

The term "cracking catalyst" as used herein refers to either new or usedcracking catalyst materials that are useful for cracking hydrocarbons inthe absence of added hydrogen. A list of typical cracking catalysts isset forth in column 4, line 30 through column 5, line 40 of U.S. Pat.No. 3,408,286. The cracking catalyst referred to can be any conventionalcracking catalyst. The term "unmodified cracking catalyst" as usedherein means any cracking catalyst which has not been modified bycontact with indium modifier.

Such cracking catalyst materials can be any of those cracking catalystsconventionally employed in the catalytic cracking of hydrocarbonsboiling above 400° F. (204° C.) for the production of gasoline, motorfuel blending components and light distillates. These conventionalcracking catalysts generally contain amorphous silica or silica-alumina.Such materials are frequently associated with zeolitic materials, i.e.aluminosilicate zeolites. These zeolitic materials can be naturallyoccurring, or they can be produced by conventional ion exchange methodssuch as to provide metallic ions which improve the activity of thecatalyst. Zeolite-modified silica-alumina catalysts are particularlyapplicable in this invention. The term zeolite is used herein isintended to include those crystalline aluminosilicates that containsodiu or calcium cations and in addition those crystallinealuminosilicates that have had sodium or calcium cations replaced withother suitable metal cations.

Examples of cracking catalysts into or onto which indium modifier can beincorporated include hydrocarbon cracking catalysts obtained by admixingan inorganic oxide gel with an aluminosilicate, and aluminosilicatecompositions which are strongly acidic as a result of treatment with afluid medium containing at least one rare earth metal cation and ahydrogen ion, or ion capable of conversion to a hydrogen ion. Thecatalytic cracking material employed will prior to use in crackinggenerally be in particulate form having a particle size principallywithin the range of about 10 to about 200 microns.

If desired, the cracking catalyst can contain a combustion promoter suchas platinum or chromium.

The unused catalytic cracking material as employed in the presentinvention contains essentially no nickel, vanadium, iron, copper orcobalt. Particularly and preferably, the nickel, vanadium, iron andcopper metals content of the unused catalytic cracking material whichconstitutes the major portion of the unused cracking catalyst of thisinvention is defined by the following limits:

    ______________________________________                                        nickel          0 to 0.2 weight percent                                       vanadium        0 to 0.6 weight percent                                       iron            0 to 0.8 weight percent                                       copper          0 to 0.02 weight percent                                      ______________________________________                                    

The weight percentages in this table relate to the total weight of theunused catalytic cracking material including the metals nickel,vanadium, iron and copper, but excluding the added indium modifyingagents. The contents of these metals on the cracking catalyst can bedetermined by standard methods well known in the art, e.g., by atomicabsorption spectroscopy or by X-ray fluorescence spectroscopy.

The catalytic cracking materials can vary in pore volume and surfacearea. Generally, however, the unused cracking catalyst will have a porevolume in the range of about 0.1 to about 1 ml/g. The surface area ofthis unused catalytic cracking material generally will be in the rangeof about 50 to about 500 m² /g.

The modified cataylst of this invention comprises a conventionalcracking catalyst having a modifying or passivating amount of indiummodifier therein or thereon. The quantity of indium modifier employed isgenerally such that about 0.005 to about 8, preferably about 0.01 toabout 2, weight percent indium is deposited on the catalyst, thesepercentages being based on the weight of cracking catalyst prior totreatment with indium modifier. The amount of indium which is mostdesirable on the catalyst will vary according to the effective level ofcontaminating metals on the catalyst, with higher values of indium beingdesirable for higher effective values of contaminating metals.

The manner in which the conventional cracking catalyst is contacted withindium modifier is not critical. For example, the indium-containingmaterial in finely divided form can be mixed with the conventionalcracking catalyst in ordinary manner such as rolling, shaking, stirringor the like. Alternatively, the indium modifier can be dissolved ordispersed in a suitable liquid, e.g., water, hydrocarbon of aqueousacid, depending in part on the particular modifying agents used, and theresulting solution or dispersion can be used to impregnate theconventional cracking catalyst, followed by volatilization of theliquid, or the indium modifier can be precipitated onto the catalystfrom solutions of the treating agents in different chemical form,followed by solvent removal. If desired, the indium-containing materialcan be dissolved in the hydrocarbon feedstock to the cracking process,in which the hydrocarbon feedstock and the modifying agent contact thecracking catalyst at about the same time. Also, if desired, the crackingcatalyst can be exposed to a vapor form of the indium-containingmaterial to deposit the agents on the catalyst. Of course, combinationsof the various methods can be employed to achieve modification of thecatalyst.

The indium compounds included within the scope of this invention asindium modifiers include any suitable indium compounds not containingthe element antimony. Suitable compounds of indium include, for example,the indium oxides In₂ O₃, InO, and In₂ O; the indium sulfides, In₂ S₃,InS, and In₂ S; indium selenide; indium telluride; indium hydroxide;indium arsenide; indium phosphate; indium nitrate; and indium sulfate.Effective but less preferable indium compounds include indiumperchlorate and the indium halides InX₃, InX₂, and InX where X can bechlorine, bromine, or iodine. These indium compounds are less preferredbecause of the corrosive effect that such halogen compounds generallyhave on metal process equipment. Suitable organic indium compounds canalso be employed. And as indicated elemental indium can be utilized as amodifier if desired.

Since the main purpose of the indium modifier on the catalytic crackingmaterial is to reduce the otherwise occurring undesirable effects ofcontaminating metals, in particular, the increased hydrogen and cokeproduction and the reduced yields of gasoline or higher-boilinghydrocarbon fuels such as kerosene, diesel fuel, and burning oils causedby these contaminating metals, the sources of indium modifier utilizedand incorporated into or onto the cracking catalyst should beessentially free of such contaminating metals. The indium modifiersources thus should contain essentially no nickel, no vanadium, no iron,no copper and no cobalt or other detrimental contaminating metal.

Prior to or during use in the hydrocarbon cracking process the indiummodified catalyst should be heated to an elevated temperature, e.g.,within the range of about 800° F. (426° C.) to about 1500° F. (816°C.),in an oxidizing or reducing atmosphere. The purpose of the heatingis to activate the catalyst. Such heating can occur in the catalyticcracker, in the catalyst regenerator, or in a vessel separate from thecatalytic cracker or catalyst regenerator. Thus the indium modifiedcatalyst can be prepared from used or new conventional cracking catalystby admixing this conventional catalyst with at least one suitable indiummodifier as above-identified in the presence or absence of a diluent,with removal of the diluent, if employed, with or without heating to anelevated temperature prior to being used in the cracking process, andthe resulting catalyst can be added as make-up catalyst for the crackingprocess, this make-up catalyst preferably being added to the catalystregenerator. In a preferred process the indium modifier as such orpreferably dissolved or dispersed in a suitable liquid, is added to theoil feedstock as the feedstock is charged to the catalytic cracker, thetreating agents being added at such a rate as to maintain theconcentration of indium in or on the catalyst generally within the rangeof about 0.005 to about 8, preferably in the range of about 0.01 toabout 2 weight percent, these percentages being based on the weight ofcracking catalyst prior to treatment with indium modifier. The additionof indium modifier can be continuous or intermittent.

In accordance with a further embodiment of this invention there isprovided a process for restoring used cracking catalyst by passivatingcontaminating metals selected from the group consisting of nickel,vanadium, iron, copper and cobalt which process comprises contacting thecontaminated cracking catalyst under an elevated temperature with atleast one indium modifier as set forth above.

The time during which the catalyst is contacted with the modifier is notcritical. Generally the time for a batch treatment of the catalyst aswith a solution of at least one modifier outside of the reaction zone isin the range of from 0.1 to 300 minutes. In a presently preferredembodiment, the indium modifier is continuously metered into thecracking reactor by being introduced into the feedstock before thefeedstock is passed to the reaction zone.

In accordance with a still further embodiment of this invention, thereis provided an improved cracking process wherein hydrocarbon feedstockis contacted under cracking conditions with a modified cracking catalystwhich comprises a modifying amount of indium modifier as defined above.For this embodiment, too, the preferred details concerning the modifiedcracking catalyst disclosed above apply. Thus, the preferred modifiedcracking catalyst is one that is obtained by mixing a cracking catalystwith the indium modifier and subjecting the modified catalyst totemperature conditions in the range of about 800° F. (426° C.) to about1500° F. (816° C.). Most preferably, the initial high-temperaturetreatment of the cracking catalyst-treating agent mixture is carried outunder reducing conditions.

Advantageously, and in accordance with a still further embodiment ofthis invention, indium modifier is added to the feedstock entering thecracking zone for contact with the cracking catalyst. By this procedurethe contacting of the cracking catalyst and indium modifier and theinitial treatment under elevated temperatures are done under thereducing conditions prevailing in the catalytic cracker.

The cracking process in which the indium-containing cracking catalyst isemployed is basically an improvement over a conventional crackingprocess which employes a conventional cracking catalyst alone. Althoughthe indium-containing cracking catalyst can be employed in a catalyticcracking process employing a fixed catalyst bed, it is especially usefulin a fluid catalytic cracking process.

A preferred embodiment of the cracking process of this inventionutilizes a cyclic flow of catalyst from a cracking zone to aregeneration zone. In this process, a hydrocarbon feedstock containingcontaminating metals such as nickel, vanadium or iron is contacted in acracking zone under cracking conditions and in the absence of addedhydrogen with indium-containing cracking catalyst as defined above; acracked product is obtained and recovered; the cracking catalyst ispassed from the cracking zone into a regeneration zone; and in theregeneration zone the cracking catalyst is regenerated by beingcontacted with a free oxygen-containing gas, preferably air. The cokethat has been built up during the cracking process is thereby at leastpartially burned off the catalyst. The regenerated cracking catalyst isreintroduced into the cracking zone.

Furthermore, it is preferred in carrying out the cracking process ofthis invention to replace a fraction of the total cracking catalyst withunused cracking catalyst continuously or intermittently. Generally,about 0.5 to about 6 weight percent of the total cracking catalyst isreplaced daily by fresh cracking catalyst. The actual quantity of thecatalyst replaced depends in part upon the nature of the feedstock used.The make-up quantity of cracking catalyst can be added at any locationin the process. Preferably, however, the cracking catalyst that ismake-up catalyst is introduced into the regenerator in a cyclic crackingprocess.

Also, it is to be understood that the used cracking catalyst coming fromthe cracking zone, before introduction into the regenerator, is strippedof essentially all entrained liquid or gaseous hydrocarbons. Similarly,the regenerated catalyst can be stripped of any entrained oxygen beforeit reenters the cracking zone. The stripping is generally done withsteam.

The specific conditions in the cracking zone and in the regenerationzone are not critical and depend upon several parameters, such as thefeedstock used, the catalyst used, and the results desired. Preferablyand most commonly, the cracking and regeneration conditions are withinthe following ranges:

    ______________________________________                                        Cracking Zone                                                                 Temperature:     800°-1200° F. (427°-649°                          C.)                                                          Time:            1-40 seconds                                                 Pressure:        Subatmospheric to 3000 psig                                  Catalyst:oil ratio:                                                                            3:1 to 30:1, by weight                                       Regeneration Zone                                                             Temperature:     1000°-1500° F. (583°-816°                         C.)                                                          Time:            240 minutes                                                  Pressure:        Subatmospheric to 3000 psig                                  Air at 60° F. (16° C.)                                                           100-250 ft.sup.3 /lb. coke                                   and 1 atmosphere:                                                                              (6.2-15.6 m.sup.3 /kg coke)                                  ______________________________________                                    

The feedstocks employed in the catalytic cracking process of thisinvention can contain metal contaminants such as nickel, vanadium, iron,copper and/or cobalt and the like. The feedstocks include those whichare conventionally utilized in catalytic cracking processes to producegasoline and light distillate fractions from heavier hydrocarbonfeedstocks. The feedstocks generally have an initial boiling point aboveabout 400° F. (204° C.) and include fluids such as gas oils, fuel oils,cycle oils, slurry oils, topped crudes, shale oils, oil from tar sands,oils from coal, mixtures of two or more of these, and the like. By"topped crude" is meant those oils which are obtained as the bottoms ofa crude oil fractionator. If desired, all or a portion of the feedstockcan constitute an oil from which a portion of the metal contentpreviously has been removed, e.g., by hydrotreating or solventextraction.

Typically the feedstock utilized in the process of this invention willcontain one or more of the metals nickel, vanadium and iron within theranges shown in the following table:

    ______________________________________                                                          Metal Content                                               Metal             of Feedstocks, ppm.sup.(1)                                  ______________________________________                                        Nickel            0.02 to 100                                                 Vanadium          0.02 to 500                                                 Iron              0.02 to 500                                                 Total metals      0.02 to 1100.sup.(2)                                        ______________________________________                                         .sup.(1) The ppm metal content refers to the feedstock as used. As used i     this table and throughout the specification, ppm means parts per million,     by weight.                                                                    .sup.(2) Total metals in this table and elsewhere refers to the sum of th     nickel, vanadium and iron contents in the feedstock that are effective in     contaminating the catalyst; the total metals content can be determined in     accordance with methods well known in the art, e.g., by atomic absorption     spectroscopy.                                                            

One of the most important embodiments of this invention resides in aheavy oil cracking process. The known commercial heavy oil crackingprocess is capable of cracking heavy oils having a metals contents of upto 80 ppm of total effective metals, i.e., metals in any formdetrimental to the cracking process. Economically marginal results areobtained with oils having 40 to 80 ppm with total effective metals. Inaccordance with this invention, heavy oils with a total metals contentof about 40 to 100 ppm and even those of about 100 to 200 ppm and aboveof total metals can be cracked in a cracking process in the absence ofadded hydrogen by utilizing the cracking catalyst defined above to yieldgasoline and other fuels and fuel blending components. Thus, known heavyoils with total metals contents of from 80 to 300 ppm, that could notheretofore be directly used for fuel production and in particular forgasoline or higher-boiling hydrocarbon fuels production, in accordancewith this invention can be cracked to yield gasoline and higher-boilinghydrocarbon fuels such as kerosene, diesel fuel and burning oils. Asindicated earlier the optimum amount of indium in or on the crackingcatalyst varies with the amount of contaminating metals in thefeedstock. The amounts of indium generally considered useful for variouslevels of contaminated metals is set forth in the following table:

    ______________________________________                                        Total V, Fe, Ni in                                                                             Indium Added                                                 Feedstock, ppm   to Catalyst, Wt. %*                                          ______________________________________                                         40-100          0.05-0.8                                                     100-200          0.1-1                                                        200-300          0.15-1.5                                                     300-800          0.2-2                                                        ______________________________________                                         *Based on the weight of catalyst prior to addition of indium passivating      agent. Quantities are expressed as the element.                          

The invention will be still more fully understood from the followingexample which illustrates an embodiment of the instant invention.

EXAMPLE

A portion of a commercial cracking catalyst that had been used in aseries of cracking steps was employed to evaluate the effect of indium.The catalyst, being a synthetic zeolite combined with clay, waspredominantly silica and alumina. Concentration of some other elementstogether with pertinent physical properties are shown in Table I.

                  TABLE I                                                         ______________________________________                                        Surface area, m.sup.2 /g                                                                        74.3                                                        Pore volume, ml/g 0.29                                                        Composition, wt. %                                                            Nickel            0.38                                                        Vanadium          0.60                                                        Iron              0.90                                                        Cerium            0.40                                                        Sodium            0.39                                                        Carbon            0.06                                                        ______________________________________                                    

A portion of this used, metals-contaminated catalyst was treated withindium as follows. To 110 g of dried catalyst was added 0.377 g of 100mesh indium (II) sulfide, InS, purchased from Cerac/Pure, Inc.,Menomonee Falls, Wisc. Catalyst preparation was done in a dry, inertatmosphere because the particular indium compound chosen was moisturesensitive and would evolve hydrogen sulfide. After mixing by stirringthe resulting powder was poured into a quartz tube reactor where, whilebeing fluidized with dry nitrogen, it was heated to 482° C.; then it wasfluidized with hydrogen while the temperature was raised to 649° C. Atthat temperature fluidization with nitrogen was continued for fiveminutes followed by a regeneration treatment involving 15 minutes oftreatment with air at that temperature after which the catalyst wascooled to ambient temperature while being fluidized with air. Thecatalyst was then subjected to 10 aging cycles. Each cycle was conductedin the following manner. The catalyst at about 482° C. was fluidizedwith nitrogen for one minute, then heated to about 510° C. during twominutes while fluidized with hydrogen, then maintained at about 510° C.for one minute while fluidized with nitrogen, then heated to about 649°C. for 10 minutes while fluidized with air, and then cooled to about482° C. during 0.5 minutes while fluidized with air. The aging cycleswere employed to insure that the modified catalyst had been exposed totreatments comparable to those to which the untreated catalyst had beenexposed in the commercial operation. After 10 such cycles the catalystwas cooled to room temperature while being fluidized with nitrogen andwas then evaluated as a cracking catalyst. This catalyst contained 0.27weight percent of added indium, based on the weight of the catalystprior to addition of the indium compound.

The relative effectiveness of the indium-treated catalyst and the usedbut untreated catalyst was evaluated using a fluidized bed reactor usinga gas oil as the feedstock to be subjected to cracking. The propertiesof the gas oil used in the cracking tests are summarized in Table II.

                  TABLE II                                                        ______________________________________                                        API gravity at 25.8° C.                                                Distillation (by ASTM D 1160-61)                                               2%                 259° C.                                            10%                 297                                                       30%                 354                                                       50%                 404                                                       70%                 450                                                       90%                 523                                                       BMCI                41.1                                                      Sulfur              0.40 wt. %                                                Nitrogen            0.07                                                      Carbon residue      0.87                                                      ______________________________________                                    

The cracking reactions were carried out at about 510° C. at atmosphericpressure for 0.5 minutes and the regeneration steps were conducted atabout 649° C. at atmospheric pressure for about 30 minutes usingfluidized air. The reactor was purged with nitrogen before and aftereach cracking step.

The cracking reactions with the untreated used catalyst were conductedat varying catalyst to oil ratios. The resulting data points providedcurves which indicated the conversion and yields for various catalyst tooil ratios. The values from the curves for a catalyst to oil ratio of7.7 are reported in Table III below for comparison with two runs usingthe treated catalyst and catalyst to oil ratios of about 7.7.

                                      TABLE III                                   __________________________________________________________________________                     Conversion                                                                          Yields                                                       Cat./Oil                                                                            Material                                                                           (Vol. %                                                                             Gasoline                                                                           SCF H.sub.2 /bbl                                                                     Coke,                                      Catalyst                                                                            Wt. Ratio                                                                           Balance                                                                            of Feed)                                                                            Vol. %                                                                             Feed Conv.                                                                           Wt. %                                      __________________________________________________________________________    Untreated                                                                           7.7   *    64.5  51.7 635    8.7                                        In treated                                                                          7.79  99.1 65.0  55.4 564    7.9                                        In treated                                                                          7.75  97.3 66.2  56.0 585    7.4                                        __________________________________________________________________________     *Greater than 95% in all runs                                            

Based on the average of the two runs, the catalyst treated with indiumyielded 7.7% more gasoline than the untreated catalyst, while producing9.5% less hydrogen and 12.1% less coke than the untreated catalyst.

Although several embodiments of the present invention have beendisclosed herein for the purpose of illustration, it will be understoodthat further variations and modifications can be made without departingfrom the spirit and scope of the present invention as defined in thefollowing claims.

What is claimed is:
 1. In the process for the catalytic cracking of ahydrocarbon feedstock containing at least one catalyst contaminatingmetal selected from the group consisting of nickel, vanadium, iron,copper, and cobalt, the improvement comprising employing a modifiedcracking catalyst produced by combining a zeolite containing crackingcatalyst with at least one modifier selected from the group consistingof elemental indium and indium compounds free of the element antimony,said at least one modifier being combined with said cracking catalyst inan amount sufficient to reduce the deleterious effects of saidcontaminating metals.
 2. A process according to claim 1 wherein theamount of indium in said modified cracking catalyst is in the range ofabout 0.005 to about 8 weight percent based on the weight of thecracking catalyst before addition of indium modifier.
 3. A processaccording to claim 2 wherein said at least one modifier is selected fromthe group consisting of elemental indium, indium oxides, indiumsulfides, indium selenide, indium telluride, indium hydroxide, indiumarsenide, indium phosphate, indium nitrate, and indium sulfate.
 4. Aprocess according to claim 3 wherein said catalyst is combined with InS.5. A process according to claims 2, 3, or 4 wherein said at least onemodifier is combined with said cracking catalyst by being included inthe hydrocarbon feedstock that is subjected to cracking over saidcracking catalyst.
 6. A process according to claim 5 wherein thecatalytic cracking of said hydrocarbon feedstock is conducted at atemperature in the range of about 427° C. to about 649° C.
 7. A processaccording to claim 6 wherein modified cracking catalyst is withdrawnfrom the cracking zone, introduced into a regeneration zone wherein itis contacted with free oxygen-containing gas to burn off coke depositedthereon, and the regenerated modified cracking catalyst is withdrawnfrom the regeneration zone and reintroduced into the cracking zone.
 8. Aprocess according to claim 7 wherein the regeneration of said modifiedcracking catalyst is conducted at a temperature in the range of about538° C. to about 816° C.
 9. A process according to claim 5 wherein thecracking catalyst comprises an aluminosilicate zeolite crackingcatalyst.
 10. A process according to claims 2, 3, or 4 wherein said atleast one modifier is combined with said cracking catalyst outside thecracking zone.
 11. A process for the catalytic cracking of a hydrocarbonfeedstock containing at least one contaminating metal selected from thegroup consisting of nickel, vanadium, iron, copper, and cobalt, saidprocess comprising contacting said feedstock with a zeolite-containingcracking catalyst under catalytic cracking conditions, wherein saidcracking catalyst is produced by combining a cracking catalyst with atleast one modifier selected from the group consisting of elementalindium and indium compounds free of the element antimony, said at leastone modifier being combined with said cracking catalyst in an amountsufficient to reduce the deleterious effects of said contaminatingmetals.
 12. A process according to claim 11 wherein said crackingcatalyst is produced by combining indium (II) sulfide with said crackingcatalyst.
 13. A process according to claim 11 or 12 wherein the amountof indium in said cracking catalyst is in the range of about 0.005 toabout 8 weight percent based on the weight of the cracking catalystbefore the addition of the indium modifier.
 14. A process for thecatalytic cracking of a hydrocarbon containing at least onecontaminating metal selected from the group consisting of nickel,vanadium, iron, copper and cobalt, said process comprising contactingsaid feedstock with a zeolite-containing cracking catalyst undercracking conditions in the presence of at least one modifier selectedfrom the group consisting of elemental indium and indium compounds freeof the element antimony, said modifier being present in an amountsufficient to reduce the deleterious effects of said contaminatingmetals.
 15. A process according to claim 14 wherein said modifier isindium (II) sulfide.
 16. A process according to claim 14 or 15 whereinsaid modifier is present in an amount in the range of about 0.005 toabout 8 weight percent based on the weight of the cracking catalystbefore the addition of the indium modifier.
 17. A process according toclaim 16 wherein before the addition of said modifier said crackingcatalyst contains at least 3800 ppm of nickel.